package com.omp.common.security;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5 {
	// 十六进制数字
	private final static String[] hexDigits = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

	/**
	 * 转换字节数组为16进制字串
	 * @param b 字节数组
	 * @return 16进制字串
	 */
	private static String byteArrayToHexString(byte[] b) {
		StringBuffer resultSb = new StringBuffer();
		for (int i = 0; i < b.length; i++) {
			resultSb.append(byteToHexString(b[i]));
		}
		return resultSb.toString();
	}

	/**
	 * 将字节转换为十六进制
	 * @param byte b 要转换的字节
	 * @return String 转换后的十六进制数
	 */
	private static String byteToHexString(byte b) {
		int n = b;
		if (n < 0) {
			n = 256 + n;
		}
		int d1 = n / 16;
		int d2 = n % 16;
		return hexDigits[d1] + hexDigits[d2];
	}

	/**
	 * 加密字符串
	 * @param String origin 要加密的字符串
	 * @return String 加密后的字符串
	 * @throws NoSuchAlgorithmException
	 */
	public static String encode(String origin) throws NoSuchAlgorithmException {
		String resultString = null;
		resultString = origin;
		MessageDigest md = MessageDigest.getInstance("MD5");
		resultString = byteArrayToHexString(md.digest(resultString.getBytes()));
		return resultString;
	}
}